Border Gateway Protocol-Multi-Protocol Label Switching virtual private networks (BGP/MPLS VPN) is a mechanism that is defined under Request for Comment 2547 (RFC 2547), which allows service providers to use their IP backbone to provide VPN services for their customers. This mechanism is based on using BGP to distribute VPN routing information to the routers in the backbone network, and using MPLS to forward VPN traffic. MPLS tunnels are created dynamically when needed, which relieves service providers of pre-provisioning large numbers (e.g., thousands) of tunnels. BGP/MPLS VPNs allow service providers to define any arbitrary topology with any number of nodes in a VPN. The service provider can create multiple VPNs using the same core network.
A service provider typically supports numerous customer VPN's across its network. The service provider needs to know how many VPNs are in the network, as well as their topology, in order to efficiently manage the network resources, illustratively, when changes (additions or deletions) to the VPNs are required. For example, service provider customers may have a partial mesh topology, and wish to implement a full mesh topology. Thus, additional resources are required to fulfill such customer need.
Current VPN discovery tools look for various predetermined patterns in a network based on route targets (RT). Route targets define which nodes (e.g., routers) are exported and imported by a provider edge (PE) router, and hence, dictate the topology of a VPN. If a predetermined pattern is found, then a VPN of a particular topology can be said to have been identified in the network. However, the current VPN discovery tools do not accurately determine the total number of VPNs in the network. For example, there may be overlapping VPNs at a node that may not get counted, or a VPN pattern may not have been examined. Therefore, there is a need in the art for a method and apparatus for determining the number of VPNs that are hosted by a service provider and their respective topologies.